The invention concerns a brush, in particular for an electric toothbrush having a brush head driven in at least one direction with bristles attached thereto.
The invention generally concerns driven brushes, in particular however those of electric toothbrushes.
Substantially two factors are important for the cleaning and massaging effect of a toothbrush on teeth and gums which are independent of whether or not the toothbrush is driven manually or electrically. These are the bristle stock and the motion with which the bristle stock is guided over the teeth and the gums. When cleaning by hand, substantially linear motions are effected along the row of teeth as well as perpendicular thereto (red-white). These are however normally overlapped with other more or less random motion components. In this manner a full area brushing effect is generally guaranteed: the bristles penetrate sufficiently into the spaces between the teeth and also into the fine fissures of the teeth surfaces. This is supported in addition through particular features of the bristle stock, e.g. V-shaped bristle bundles, non-planar shapes, contoured brush surfaces and the like.
With electric toothbrushes which are normally held in a particular position by the user and are guided in a substantially linear fashion, the components of motion, in contrast to the random manual guidance of the hand toothbrush, are limited by the drive mechanism. With elongated brush heads, similar to the hand toothbrushes, a combination of linear (axial) and pivoting motion is conventional. With round brush heads, rotational motion, sometimes superimposed by an upward and downward motion in the direction of the bristles, is preferred. Finally, bristle heads having drives are known in the art with which a few bristle bundles are displaced normally in pairs in rotational oscillation. The more components of motion the more complex the drive and the greater its susceptibility to failure.
The brush head of a conventional electric toothbrush (US 5 173 983) has a soft peripheral edge at which the brush head is supported on the teeth surfaces or on the gums. The bristle stock is mounted in a recessed manner within this soft peripheral edge. The bristles protrude past the peripheral edge. They are disposed in a manner similar to a bucket wheel and extend from the center of rotation of the brush head in an outward direction in three curved strips. The bristles disposed at the center are somewhat longer than the others and join together into a spike for penetrating, in particular, into inter-dental cavities and between the teeth and the edge of the gums. With this conventional brush head, the degree of pressing of the bristles is limited by the seating of the peripheral edge and decreases as the bristles wear. In addition, brushing action is effected only by a fraction of the brush head, since there are no bristles between the curved bristle strips. This leads to a reduction in effectiveness. The brushing direction is limited to the direction of rotation of the brush head. Residual food particles, soiling, and residual toothpaste settle into the recessed region within the soft peripheral edge and near the lower ends of the bristle bundles.
This purpose is achieved with a driven brush head having bristles attached thereto in that the ends of at least one portion of the bristles protrude beyond the remaining evenly covering bristle-stock and are disposed within a striped or spotted enveloping surface and at least the border edge of the enveloping surface formed by the leading bristles in the direction of motion of the brush head extends at an angle relative to the direction of motion of the brush head which differs from 90xc2x0.
The angular position of the border edge of the enveloping surface formed by the protruding bristles relative to the direction of motion of the brush head results in at least one component of motion at an angle with respect to the component of motion given by the drive. If the border edge is not linear, rather has a plurality of angles or is corrugated or has a plurality of enveloping surfaces with different angles relative to the direction of motion of the drive, a plurality of motional directions thereby result with an associated plurality of cleaning and massaging effects. The shorter, evenly covering bristle stock thereby guarantee full surface brushing. The brush head seats at this shorter bristle stock during brushing, wherein the protruding bristles can also penetrate into the inter-dental spaces and beneath the edge of the gums.
The leading and trailing border edges of the enveloping surface formed by the bristles can be substantially parallel so that a strip-shape bristle surface results. The two border edges can also extend at differing angles relative to the direction of motion of the brush head so that spotted brush surfaces result which are particularly effective with an oscillating drive since, in dependence on the direction of motion of the drive, further additional components of motion are overlapped in various directions.
The dependent claims recite various preferred embodiments for a brush head driven to rotate about an axis or oscillate. Among these embodiments, only two are focused upon here. In the event of a spiraling enveloping surface, the rotation or rotational oscillation motion is overlapped with additional circular motion of variable radius. The same is true for an S-shaped configuration of the enveloping surface particularly when a plurality of S-shaped striped enveloping surfaces are provided, similar to the shape of a bucket wheel.
The dependent claims characterize embodiments with an elongated brush head having a linear drive in the direction of the longitudinal axis which, if appropriate, can be overlapped-by an oscillating pivoting motion perpendicular thereto. In particular, zigzagged or arrow shaped striped enveloping surfaces have turned out to be especially effective.
The invention is described below with reference to the embodiment shown in the drawing.